[REFACTORING] rename a method
make TraditionalDiffTokenMapper store token mapping in a map whose keys are file IDs of old source files
add a class to represent mapping of clone class
add a class to represent mapping of code fragments
implement equals, hashCode, and toString
add clone class mapping with volatile data
add code fragment mapping with volatile data
add interfaces to detect mapping of clones and code fragments
[BUG_FIX] make CloneClassBuildTask compare tokens with specified equalizer
add a class to represent intermediate instance for mapping segments between versions with iClone algorithm
add a helper class to estimate the next state of every code fragment and segment